Liquid nitrogen isn't particularly dangerous as long as you don't do anything stupid (i.e. drink it or pour it into a sealed container). It is obviously not toxic (but you should never use it in small badly ventilated spaces, e.g. elevators) and getting some on your skin won't hurt you at all as long as it doesn't get trapped in or underneath something (e.g. tight clothes, underneath jewelry). When doing experiments like this I would suggest wearing a T-shirt (again, getting droplets on your skin won't hurt you at all) or loose fitting garments.
Do be very careful if wearing gloves, there are many situations where they are appropriate (if you e.g. might need to touch a metal surface that has been cooled down by the nitrogen), but there is always the risk of getting nitrogen inside the glove (which would be bad).
It is certainly less dangerous to handle than for example boiling water. In fact, "treat it as boiling water" is exactly what I tell students when I teach them how to handle nitrogen.
That said, anyone using it for the first time should be obviously be supervised; and I wouldn't give it to a bunch of small kids. However, it anyone older than say 15 should be fine as long as they are properly supervised.
(I have been using liquid nitrogen/helium on daily basis for 16 years, and I also used to supervise lab exercises in cryogenics and superconductivity back when I was a PhD student; including demos using a Meissner kit)